Lack of the PGA exopolysaccharide in Salmonella as an adaptive trait for survival in the host
Fecha
2017Autor
Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
Versión publicada / Argitaratu den bertsioa
Impacto
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10.1371/journal.pgen.1006816
Resumen
Many bacteria build biofilm matrices using a conserved exopolysaccharide named PGA or
PNAG (poly-β-1,6-N-acetyl-D-glucosamine). Interestingly, while E. coli and other members
of the family Enterobacteriaceae encode the pgaABCD operon responsible for PGA synthesis,
Salmonella lacks it. The evolutionary force driving this difference remains to be determined.
Here, we report that Salmonella lost ...
[++]
Many bacteria build biofilm matrices using a conserved exopolysaccharide named PGA or
PNAG (poly-β-1,6-N-acetyl-D-glucosamine). Interestingly, while E. coli and other members
of the family Enterobacteriaceae encode the pgaABCD operon responsible for PGA synthesis,
Salmonella lacks it. The evolutionary force driving this difference remains to be determined.
Here, we report that Salmonella lost the pgaABCD operon after the divergence
of Salmonella and Citrobacter clades, and previous to the diversification of the currently
sequenced Salmonella strains. Reconstitution of the PGA machinery endows Salmonella
with the capacity to produce PGA in a cyclic dimeric GMP (c-di-GMP) dependent manner.
Outside the host, the PGA polysaccharide does not seem to provide any significant benefit
to Salmonella: resistance against chlorine treatment, ultraviolet light irradiation, heavy metal
stress and phage infection remained the same as in a strain producing cellulose, the main
biofilm exopolysaccharide naturally produced by Salmonella. In contrast, PGA production
proved to be deleterious to Salmonella survival inside the host, since it increased susceptibility
to bile salts and oxidative stress, and hindered the capacity of S. Enteritidis to survive
inside macrophages and to colonize extraintestinal organs, including the gallbladder. Altogether,
our observations indicate that PGA is an antivirulence factor whose loss may have
been a necessary event during Salmonella speciation to permit survival inside the host. [--]
Materias
PGA exopolysaccharide,
Salmonella
Editor
Public Library of Science
Publicado en
Plos Genetics, 13(5): e1006816
Departamento
Universidad Pública de Navarra/Nafarroako Unibertsitate Publikoa. IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Versión del editor
Entidades Financiadoras
This work was supported by the Spanish Ministry of Economy and Competitiveness grants BIO2014-53530-R and SAF2014-56716-REDT. JV was supported by Ramon y Cajal (RYC-2009-03948) contract from the Spanish Ministry of Economy and Competitiveness.